Referring to FIGS. 1-2, the ear (10) is divided into three parts: an external ear (12), a middle ear (14) and an inner ear (16). The external ear (12) consists of an auricle (18) and ear canal (20) that gather sound and direct it toward a tympanic membrane (22) (also referred to as the eardrum) located at an inner end (24) of the ear canal (20). The middle ear (14) lies between the external and inner ears (12, 16) and is connected to the back of the throat by a Eustachian tube (ET) (26), which serves as a pressure equalizing valve between the ear (10) and the sinuses. The ET (26) terminates in a pharyngeal ostium (28) in the nasopharynx region (30) of the throat (32). In addition to the eardrum (22), the middle ear (14) also consists of three small ear bones (ossicles): the malleus (34) (hammer), incus (36) (anvil) and stapes (38) (stirrup). These bones (34, 36, 38) transmit sound vibrations to the inner ear (16) and thereby act as a transformer, converting sound vibrations in the canal (20) of the external ear (12) into fluid waves in the inner ear (16). These fluid waves stimulate several nerve endings (40) that, in turn, transmit sound energy to the brain where it is interpreted.
The ET (26) is a narrow, one-and-a-half inch long channel connecting the middle ear (14) with the nasopharynx (30), the upper throat area just above the palate, in back of the nose. The ET (26) functions as a pressure equalizing valve for the middle ear (14), which is normally filled with air. When functioning properly, the ET (26) opens for a fraction of a second periodically (about once every three minutes) in response to swallowing or yawning. In so doing, it allows air into the middle ear (14) to replace air that has been absorbed by the middle ear lining (mucous membrane) or to equalize pressure changes occurring on altitude changes. Anything that interferes with this periodic opening and closing of the ET (26) may result in hearing impairment or other ear symptoms.
Obstruction or blockage of the ET (26) results in a negative middle ear (14) pressure, with retraction (sucking in) of the eardrum (22). In adults, this is usually accompanied by some ear discomfort, a fullness or pressure feeling and may result in a mild hearing impairment and head noise (tinnitus). There may be no symptoms in children. If the obstruction is prolonged, fluid may be drawn from the mucous membrane of the middle ear (14), creating a condition referred to as serous otitis media (fluid in the middle ear). This occurs frequently in children in connection with an upper respiratory infection and accounts for the hearing impairment associated with this condition.
A lining membrane (mucous membrane) of the middle ear (14) and ET (26) is connected with, and is the same as, the membrane of the nose (42), sinuses (44) and throat (32). Infection of these areas results in mucous membrane swelling which in turn may result in obstruction of the ET (26). This is referred to as serous otitis media, which as discussed above is essentially a collection of fluid in the middle ear (14). Serous otitis media can be acute or chronic, and may be the result of blockage of the pharyngeal ostium (28) of the ET (26), which leads to the accumulation of fluid in the middle ear (14). In the presence of bacteria, this fluid may become infected, leading to an acute suppurative otitis media (infected or abscessed middle ear). When infection does not develop, the fluid remains until the ET (26) again begins to function normally, at which time the fluid is absorbed or drains down the tube into the throat (32) through the ET (26) pharyngeal ostium (28).
Chronic serous otitis media may result from longstanding ET blockage, or from thickening of the fluid so that it cannot be absorbed or drained down the ET (26). This chronic condition may lead to hearing impairment. There may be recurrent ear pain, especially when the individual catches a cold. Fortunately, serous otitis media may persist for many years without producing any permanent damage to the middle ear mechanism. The presence of fluid in the middle ear (14), however, makes it very susceptible to recurrent acute infections. These recurrent infections may result in middle ear damage.
When the ET (26) contains a build-up of fluid, a number of things may occur. First, the body may absorb the air from the middle ear (14), causing a vacuum to form that tends to pull the lining membrane and ear drum (22) inwardly, causing pain. Next, the body may replace the vacuum with more fluid which tends to relieve the pain, but the patient can experience a fullness sensation in the ear (10). Treatment of this condition with antihistamines and decongestants can take many weeks to be fully effective. Finally, the fluid can become infected, which can lead to pain, illness, and temporary hearing loss. If the inner ear (14) is affected, the patient may feel a spinning or turning sensation (vertigo). The infection may be treated with antibiotics.
However, even if antihistamines, decongestants, and antibiotics are used to treat an infection or other cause of fluid build-up in the middle ear (14), these treatments may not immediately resolve the pain and discomfort caused by the buildup of fluid in the middle ear (14). The most immediate relief may be felt by the patient if the fluid can be removed from the ET (26).
Antibiotic treatment of middle ear infections may result in normal middle ear function within three to four weeks. During the healing period, the patient can experience varying degrees of ear pressure, popping, clicking and fluctuation of hearing, occasionally with shooting pain in the ear. Resolution of the infection may leave the patient with uninfected fluid in the middle ear (14), localized in the ET (26).
Fluid build-up caused by these types of infections may be treated surgically. The primary objective of surgical treatment of chronic serous otitis media may be to reestablish ventilation of the middle ear, keeping the hearing at a normal level and preventing recurrent infection that might damage the eardrum membrane and middle ear bones. One method to opening the ET (26) includes the “Valsalva” maneuver, accomplished by forcibly blowing air into the middle ear (14) while holding the nose, often called popping the ear. This method may be effective for opening the ET (26) but it may not clear the accumulated fluid from the middle ear (14) and is essentially a temporary fix when fluid is present in the middle ear (14).
Methods for treating the middle ear (14) and the ET (26) include those disclosed in U.S. Patent Pub. No. 2010/0274188, entitled “Method and System for Treating Target Tissue within the ET,” published on Oct. 28, 2010, now abandoned, the disclosure of which is incorporated by reference herein; U.S. Patent Pub. No. 2013/0274715, entitled “Method and System for Eustachian Tube Dilation,” published on Oct. 17, 2013, the disclosure of which is incorporated by reference herein; and U.S. patent application Ser. No. 14/317,269, entitled “Vent Cap for a Eustachian Tube Dilation System,” filed Jun. 27, 2014, published as U.S. Pub. No. 2015/0374963 on Dec. 31, 2015, the disclosure of which is incorporated by reference herein. As described in those references, functioning of the ET (26) may be improved by dilating the ET (26) with an expandable dilator instrument.
While a variety of surgical instruments have been made and used, it is believed that no one prior to the inventors has made or used the invention described in the appended claims.